Atomic Structure Lab - Identifying Positive Ions

Atomic Structure Lab - Identifying Positive Ions introduction to atomic structure worksheet unit atomic structure worksheet answers atomic structure worksheet 8th grade answer key basic atomic structure worksheet answer sheet atomic structure quiz pdf the 3 particles of the atom are the number of protons in one atom of an element determines the atoms protons neutrons and electrons practice worksheet atomic structure worksheet 7th grade atomic structure worksheet label the parts of an atom on the diagram below atomic structure worksheet 8th grade answer key
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Flame Tests – Identifying Metal Ions

Atomic Structure Lab Activity

Background and Theory

Chemists are often required to test samples to find out if they contain specific ions or compounds. This lab allows students to practice these techniques and identify the different metal ions.

When atoms are heated they become excited causing the electrons to jump into higher energy levels. These higher energy levels are less stable. As the electrons return back to their original positions, the energy is released as light energy.  Group 1 elements in the periodic table are known as the alkali metals. They include lithium, sodium and potassium, which all react vigorously with air and water.

Group 2 metals are known as the alkaline earth metals and include beryllium, barium, magnesium, calcium and strontium.   Both groups one and two metals have a distinct flame color which allows us to identify the presence of a metal ion in a solid sample.

Curriculum Links on Atomic Structure:

  • HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
  • HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

Specific Learning Objectives:

  1. Identify the positive ion in a substance.
  2. Carry out an analytical test to identify metal ions.
  3. Describe how electrons can move between energy levels.

Lab Part 1: Flame Tests for Metals

 Pre-lab Questions:

  1. Name the group one alkali metals
  2. Give the chemical formula for each of the IONS of the group one
  3. What do the group one metals have in common?
  4. Name the group two alkaline earth metals.
  5. Give the chemical formula for each of the IONS of the group two metals.
  6. What do the group two metals have in common?

Practical Activity:

You will need:

  1. Bunsen burners
  2. Flame test wires (one per two students)
  3. Hydrochloric acid
  4. Labelled solid samples of the metals you plan to test:
    • Copper chloride
    • Potassium iodide
    • Calcium chloride
    • Strontium chloride
    • Lithium chloride
    • Barium chloride
    • Sodium chloride
  5. Three mystery samples from the above list labelled ‘W’, ‘X’ and ‘Y’

Method:

  1. Dip a flame test wire into hydrochloric acid and then hold it in a blue Bunsen flame.
  2. Dip the wire into a sample of the compound and place it into the edge of a blue Bunsen flame. The flame color produced indicates which metal ion is present in the compound.
  3. Clean the wire loop and continue testing with other samples.

Name of Substance

Ion present

Flame color

Copper chloride Copper, Cu 2+ Blue-green with white flashes
Potassium iodide Potassium, K+ Violet
Calcium chloride Calcium, Ca2+ Orange-red
Strontium chloride Strontium, Sr 2+ Crimson red
Lithium chloride Lithium, Li+ Red
Barium chloride Barium,  Ba2+ Pale yellow-green
Sodium chloride Sodium, Na+ Yellow-Orange

Lab Part 2: Identifying Unknown Samples

Students test each mystery sample and then identify them using their information they found in part one.

Atomic Structure Lab Sheets

Download and print the following to use with your Atomic Structure Lab Activity

1-4 Identifying Positive Ions - Lab Answers (Doc)

1-4 Identifying Positive Ions - Lab Answers (PDF)

1-4 Identifying Positive Ions - Lab (Doc)

1-4 Identifying Positive Ions - Lab (PDF)

1-4 Identifying Positive Ions - Student Lab Sheet (Doc)

1-4 Identifying Positive Ions - Student Lab Sheet (PDF)

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Atomic Structure Lab - Identifying Positive Ions - introduction to atomic structure worksheet unit atomic structure worksheet answers atomic structure worksheet 8th grade answer key basic atomic structure worksheet answer sheet atomic structure quiz pdf the 3 particles of the atom are the number of protons in one atom of an element determines the atoms protons neutrons and electrons practice worksheet atomic structure worksheet 7th grade atomic structure worksheet label the parts of an atom on the diagram below atomic structure worksheet 8th grade answer key

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